ENHANCED IMMUNOSUPPRESSIVE ACTIVITY ASSOCIATED WITH METASTATIC LYMPHOMA-CELLS

Earlier reports from our laboratory showed that Abelson virus-induced, highly malignant and liver metastatic RAW117-H10 cells, but not the p arental, less metastatic RAW117-P cells, inhibited both T-cell and B-c ell mitogen-induced proliferation of syngeneic normal murine spleen ce lls. Similar inhibition was also noted when RAW117-H10 cell surface mo lecules extracted with butanol were used instead of whole tumor cells. In this report we describe the suppressive properties of the butanol- extracted RAW117-H10 cell surface molecules on other immune functions and the isolation/purification of a molecule from RAW117-H10 cell buta nol extract which shows inhibitory activity. The immunosuppressive mol ecules also inhibit natural killer cell-mediated cytotoxicity, lymphok ine-activated killer cell-mediated cytotoxicity, and bone marrow colon y-forming unit-granulocyte-macrophage colony formation, but not colony -forming unit-fibroblast colony formation. The suppressive molecules i nhibit interleukin 2 production by the T-lymphocytes. One of the molec ules responsible for some of the immunosuppressive activity has been i solated and purified from butanol extracts of the metastatic RAW117-H1 0 cells by preparative isoelectrofocusing techniques. The suppressive molecule has an isoelectric point of 4.3 with an approximate molecular weight of 70,000. Metastatic RAW117-H10 lymphoma cells therefore expr ess immunosuppressive molecules, which may facilitate their growth and metastasis in vivo.